Sensor assembly tethered within catheter wall

ABSTRACT

A distal tip assembly for an elongate medical device having an axis comprises a shaft having a proximal end portion, a distal end portion, a wall, and a central lumen extending axially between said proximal end portion and said distal end portion. The distal tip assembly further comprises a position sensor disposed in an outer sleeve such that the sensor can shift relative to the sleeve. The sleeve is disposed at least in part in the wall and is substantially fixed thereto.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/098,969, filed 2 May 2011, now pending, which is hereby incorporatedby reference as though fully set forth herein.

BACKGROUND OF THE INVENTION a. Field of the Invention

The present disclosure relates to a family of positioning sensors for amedical device and a method for mounting an electromagnetic positioningsensor on a medical device to avoid potential damage due to compressionand tension forces and the like.

b. Background Art

Various diagnostic and therapeutic procedures in or on the body of apatient, such as in the heart or elsewhere in the circulatory system,can be performed or facilitated by inserting an electrophysiology (EP)catheter into a body lumen and thereafter navigating the diagnostic ortherapeutic EP catheter to the target anatomical site. The EP cathetercan include one or more electrodes to be used for therapeutic (e.g.,ablation), diagnostic, or other purposes.

For certain procedures, it is desirable for the distal end of an EPcatheter to have a particular curve or shape or to include uni- orbi-directional deflection elements, for example. For example, someablation or mapping procedures on certain portions of the heart or thevasculature around the heart, such as the superior pulmonary vein, canbe simplified through the use of an EP catheter having a lariat orspiral shape on its distal end. In order to achieve the desired shape,an EP catheter can incorporate one or more shape wires that can bepreformed to the desired shape, deformed (e.g., via loading) to guidethe catheter to the target anatomical site, then unloaded such that theshape wire—and thus the catheter—returns to the preformed desired shape.

It is also known to configure straight EP catheters (i.e., without shapewires) to include one or more electromagnetic field (position) sensorsfor navigating the catheter to the target anatomical site. Whileenabling sensor-based navigation functionality, a straight EP catheteras described above does not have the same applicability to certain EPprocedures as does a shaped EP catheter.

There is therefore a need for a catheter that incorporates a shape wireand one or more electromagnetic position sensors that minimizes oreliminates one or more of the problems set forth above.

BRIEF SUMMARY OF THE INVENTION

This disclosure is directed to an elongate medical device configured foruse with a positioning system (i.e., the device includes at least oneposition sensor, such as an impedance-sensing electrode, ametallic/magnetically-responsive coil, and/or an acoustically-responsiveelement or the like). A distal tip assembly for an exemplary elongatemedical device having an axis includes a shaft having a proximal endportion, a distal end portion, a wall, and a central lumen extendingaxially between the proximal end portion and the distal end portion. Theassembly further includes one of an electromagnetic position sensor, animpedance-sensing electrode, and an acoustically-responsive elementdisposed in an outer sleeve and/or coupled to a stress-reduction flexcircuit or other member. The mechanical stress imparted to the sensor isreduced because the sleeve substantially separates the sensor from thewall, so the sensor can potentially shift relative to the sleeve, thewall, or any anchoring location therefor. The sleeve is disposed, atleast in part, in the wall and is fixed thereto in a stress-relievingconfiguration. In an embodiment, the assembly is incorporated into adevice that also includes a shape wire for providing a desired preformedshape. The sensor-in-sleeve arrangement described above allows thesensor to move with respect to the shape wire or other deflectionmechanism when assembled for use in a medical procedure. This permittedmovement avoids damage to the sensor that can otherwise occur had thesensor been rigidly fixed in the wall.

A method of fabricating a distal tip assembly for the exemplary deviceincludes a number of steps that include providing a first shaft layerand placing, at a distal end portion of the elongate medical device, aposition sensor assembly on the first shaft layer. The position sensorassembly includes a tubular core, an electrically-conductive coil woundon said core, and an outer sleeve surrounding the core and the coil. Themethod further includes applying a second shaft layer radially-outwardlyof the position sensor assembly and of the first shaft layer, andsubjecting the tip assembly to a reflow lamination process. In thereflow lamination process, the first shaft layer and the second shaftlayer bond to an outer surface of the sleeve, and the coil and the corecan shift within the sleeve.

These and other benefits, features, and capabilities are providedaccording to the structures, systems, and methods depicted, describedand claimed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified view of a first embodiment of an elongate medicaldevice, with a distal lariat portion, within a human heart.

FIGS. 2-6 illustrate a method of fabricating a distal tip assembly forthe device shown in FIG. 1.

FIG. 7 is a top view of the distal tip assembly of the first embodimentat the stage of fabrication shown in FIG. 5.

FIGS. 8 and 8A are cross-sectional views of the distal tip assembly ofthe first embodiment.

FIG. 9 is an isometric view of a distal end portion of the firstembodiment.

FIG. 10 is a cross-sectional view of the extreme distal end of the firstembodiment, taken substantially along line 10-10 in FIG. 9.

FIG. 11 is an isometric view of the first embodiment, including aproximal end portion.

FIG. 12 is a side view of a distal portion of another embodiment of anelongate medical device, having a flex circuit, with a portion of theouter jacket cut away.

FIG. 13 is a cross-sectional view of an embodiment of an elongatemedical device, taken substantially along line 13-13 in FIG. 12.

FIGS. 14-17 are various isometric and plan views of an embodiment of aflex circuit according to the disclosure.

FIGS. 18-19 are plan views of an embodiment of a flex circuit accordingto the instant disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein like reference numerals are usedto identify identical components in the various views, FIG. 1 is asimplified view of a first embodiment of an elongate medical device 10.Device 10, shown as a catheter, is disposed in the left atrium of ahuman heart 12. As depicted, device 10 comprises a spiralelectrophysiology (EP) mapping catheter incorporating at least oneelectromagnetic-, impedance-, or acoustic-based position sensor, thoughthe present invention can also find use with a spiral EP ablationcatheter, another EP catheter, or another medical device for which anelectromagnetic position sensor would be useful. A spiral mappingcatheter, such as catheter 10, can be particularly useful for mappingingress and egress points of the human heart, such as superior pulmonaryvein 14, as well as for other portions of the human vasculature. An EPmapping catheter can be used in the heart and vasculature to collect EPdata as described in greater detail in commonly-owned U.S. Pat. No.7,774,051, entitled “System and Method for Mapping ElectrophysiologyInformation Onto Complex Geometry,” which is hereby incorporated byreference in its entirety. Device 10, or another device employing anelectromagnetic position sensor and/or EP electrodes, can be used with avariety of navigation and mapping systems such as, for example, anENSITE VELOCITY system running a version of the ENSITE NavX™ softwarecommercially available from St. Jude Medical, Inc., of St. Paul, Minn.and as also seen generally by reference to U.S. Pat. No. 7,263,397entitled “Method and Apparatus for Catheter Navigation and Location andMapping in the Heart” to Hauck et al., owned by the common assignee ofthe present disclosure, and hereby incorporated by reference in itsentirety. Device 10 can also find use with other known technologies forlocating/navigating a catheter in space (and for visualization),including for example, the CARTO visualization and location system ofBiosense Webster, Inc., (e.g., as exemplified by U.S. Pat. No. 6,690,963entitled “System for Determining the Location and Orientation of anInvasive Medical Instrument,” hereby incorporated by reference in itsentirety), the AURORA® system of Northern Digital Inc., a magnetic fieldbased localization system such as the gMPS system based on technologyfrom MediGuide Ltd. of Haifa, Israel and now owned by St. Jude Medical,Inc. (e.g., as exemplified by U.S. Pat. Nos. 7,386,339, 7,197,354 and6,233,476, all of which are hereby incorporated by reference in theirentireties) or a hybrid magnetic field-impedance based system, such asthe CARTO 3 visualization and location system of Biosense Webster, Inc.(e.g., as exemplified by U.S. Pat. No. 7,536,218, and 7,848,789 both ofwhich are hereby incorporated by reference in its entirety).

An EP catheter employing one or more shape wires can include one or moreelectromagnetic position sensors for navigating the catheter to thetarget anatomical site with one or more of the technologies describedabove. Assembling electromagnetic coil sensors within the spaceconstraints of a catheter without sacrificing sensitivity presentsvarious design and manufacturing challenges. One such challenge isincorporating a sensor in a portion of a catheter that can be bent by ashape wire in a way that can place stress on the shaft of the catheterand on components disposed within the shaft, such as an electromagneticsensor.

FIGS. 2-6 are diagrammatic cross-sectional side views of a reflowmandrel assembly in various stages of build-up in a method ofmanufacture of a distal tip assembly 40 with an electromagnetic positionsensor for device 10. It should be understood that although gaps areshown between the several layers of material, such gaps are shown forvisual clarity and can or cannot be present in the actual manufacturingprocess and final product. Elements shown in FIGS. 2-6 are notnecessarily to scale. Furthermore, “assembly 40” is used herein to referboth to the distal tip assembly as it is built up and constructed, aswell as to the finished distal tip assembly.

FIG. 2 shows a mandrel 16 having a central axis “A,” a distal endportion 18, and a proximal end portion 20. Mandrel 16 can be circular inradial cross-section and have a desired length in view of the elongatemedical device or portion thereof to be manufactured. Mandrel 16 canhave grooves to facilitate the application and removal of materials, orcan be smooth.

As shown in FIG. 3, a first segment 22 ₁ of a first shaft layer 22 canfirst be placed over mandrel 16. First shaft layer 22 can consist ofmultiple segments 22 ₁, 22 ₂, 22 ₃ (best shown in FIGS. 5 and 6). Firstshaft layer 22 can be any suitable tubing material known in the art ofmedical instruments, such as engineered nylon resins and plastics,including but not limited an elastomer commercially available under thetrade designation PEBAX® from Arkema, Inc. of a suitable durometer,melting temperature and/or other characteristics. First segment 22 ₁ canhave an axial length configured to be substantially equal to the lengthof a sensor or sensor assembly to be incorporated into distal tipassembly 40.

A position sensor assembly 24 can be provided for position sensing anddevice navigation in the finished device 10. As shown in FIGS. 4 and 4A,position sensor assembly 24 can be placed on top of first shaft layer22. In the illustrated first embodiment, sensor assembly 24 is placed onfirst segment 22 ₁. Sensor assembly 24 can include a sensor 26 within anouter protection sleeve, or tube, 28. Sensor 26 can be anelectromagnetic field-detecting coil-type sensor, as shown.Electromagnetic coil sensor 26 can comprise a tubular core 30 and anelectrically-conductive coil 32 wound around core 30. Core 30 can be ahollow tube made of a polymer with a relatively high melting point, suchas polyimide, so as to maintain shape during a high-temperature reflowlamination process, such as seen by reference to co-pending U.S. patentapplication Ser. No. 12/982,120, entitled “Electromagnetic Coil Sensorfor a Medical Device,” hereby incorporated by reference in its entirety.Core 30 can also be solid, rather than hollow (shown in FIG. 13). Core30 can have a central axis “B” that is substantially parallel with, butradially offset from, mandrel central axis “A.” Because axis “A” canalso be the central axis of device 10 and distal tip assembly 40, sensoraxis “B” can be substantially parallel with, but radially offset from,axis “A” of device 10. Coil 32 can be made of electrically-conductivewire wrapped around core 30. Coil 32 is not limited in number or pitchof windings, or type of wire, but instead can be tailored to suit aparticular application of sensor 26. Coil 32 can have one or more freeleads 34 at its proximal end for connection to one or more wires 36.Wiring 36 can be coupled to coil leads 34 and extend towards theproximal end of device 10 to provide electrical connection with apositioning system, navigation system, or other system. One or morewires 36 can be in the form of a twisted-pair (TP) cable as shown inFIGS. 4-6, can be a coaxial cable, or can be another electrical signalor power cable known in the art.

Outer sleeve 28 can be provided to prevent sensor 26 from being directlyembedded in the shaft of finished device 10. Sleeve 28 can extend bothdistally and proximally beyond the axial length of sensor 26 (i.e., bothcore 30 and coil 32) and can fully circumferentially surround sensor 26(again, both core 30 and coil 32). Sleeve 28 can have a length that issubstantially the same as the length of first shaft layer segment 22 ₁.Sleeve 28 can be made of expanded polytetrafluoroethylene (ePTFE),polytetrafluoroethylene (PTFE), polyimide, fluorinated ethylenepropylene (FEP), polyether ether ketone (PEEK), or other materialinterposed between first shaft layer 22 and other shaft layers andsensor 26, which prevents such shaft layers from encapsulating and thusrigidly fixing sensor 26 therein during a high-temperature reflowlamination process. Sleeve 28 can be circumferentially sealed and can besealed at its distal end, but can have a hole at its proximal end forwiring 36 or sensor coil leads 34 to extend into or out of sleeve 28.

As shown in FIG. 5, the rest of first shaft layer 22 can then be placedon mandrel 16—i.e., segments 22 ₂ and 22 ₃ can be placed proximally anddistally of segment 22 ₁. Wiring 36 can be disposed radially-inwardly offirst shaft layer segment 22 ₂—i.e., the segment axially proximal ofsensor 26—so that wiring 36 can be disposed in the central lumen of thefinished device. Segment 22 ₂ is shown as asymmetrical across axis “A”to better show wiring 36, but segment 22 ₂ can be applied as asubstantially symmetrical segment, such as a tube. Segments 22 ₁, 22 ₂,22 ₃ can have axial lengths and radial thicknesses that are differentfrom each other, or they can have the same relative lengths andthicknesses. As noted hereinabove, the axial length of segment 22 ₁ canbe selected relative to the size of sensor 26 or sensor assembly 24. Theaxial lengths of segments 22 ₂ and 22 ₃ can be selected according to thedesired placement of one or more sensors 26 in device 10. Segments 22 ₂and 22 ₃ can have thicknesses substantially equal to each other, whichcan be greater than the thickness of segment 22 ₁.

FIG. 7 is a top view of sensor assembly 26 disposed on—i.e., layingon—first layer segment 22 ₁ at the same stage of construction as FIG. 5.Sensor core 30 has an axial length L₁, which can be less than axiallength L₂ of sleeve 28, which can be substantially equal to length L₃ offirst shaft segment 22 ₁. Sleeve axial length L₂ is shown smaller thanfirst shaft segment length L₃ for visual clarity, though L₂ can besubstantially equal to L₃ or can even be larger than L₃.

A second shaft layer 38 can then be placed over the entire distal tipassembly 40, as shown in FIG. 6, including first shaft layer 22 andsensor assembly 24. Second shaft layer 38 can be the same material asthe first shaft layer (i.e., a melt-processing polymer such as PEBAX®).Second shaft layer 38 can have the same radial thickness as thickerfirst shaft layers 22 ₂ and 22 ₃.

After second shaft layer 38 is added to the assembly, the assembly canbe subjected to a reflow lamination process, which involves heating theassembly until first shaft layer 22 and second shaft layer 38 flow andredistribute around the circumference of the assembly, bonding with anouter surface of sleeve 28 to embed sleeve 28. In one embodiment, thereflow process includes heating the assembly to about 450° F. (e.g., inan oven-like appliance), though the reflow temperature can vary forother embodiments. The assembly can then be cooled, after which firstshaft layer 22 and second shaft layer 38 form a unitary shaft 42. Shaft42 can have a proximal end portion and distal end portion coincidentwith mandrel proximal end portion 20 and mandrel distal end portion 18,respectively.

FIGS. 8 and 8A illustrate distal tip assembly 40 after the reflowlamination process and after the removal of mandrel 16. Shaft 42 has acentral lumen 44 extending along axis “A” (formerly the central axis ofmandrel 16) between the proximal end portion of shaft 42 and the distalend portion of shaft 42. Protection sleeve 28 can be embedded within awall 50 of shaft 42, but the outer diameter (O.D.) of sensor 26 can beseparated from, or at least not bonded to, the inner diameter (I.D.) ofsleeve 28, so sensor 26 can remain free to move (e.g., shift) relativeto sleeve 28. It should be understood that although a relatively largegap is shown between the I.D. of sleeve 28 and the O.D. of sensor 26(i.e., outside surface of coil 32), sleeve 28 can be relatively tight tocoil 32 and core 30 after the reflow lamination process, while stillallowing coil 32 and core 30 to shift relative to sleeve 28 and wall 50.

FIG. 9 is an isometric view of a distal end portion 54 of device 10after the addition of a tip electrode 46 and a shape wire 48 (best shownin FIG. 10) to distal tip assembly 40. Shape wire 48 can extend throughdistal end portion 54 and further proximally through device 10 and canbe configured to establish a pre-defined shape for distal end portion54. In device 10, shape wire 48 establishes a lariat shape along a planesubstantially perpendicular to device axis “A”. Shape wire 48 can be asuper-elastic or shape memory metallic alloy, such as Nitinol, oranother super-elastic or shape memory material. In a super-elasticembodiment, shape wire 48 can be pre-formed to a desired shape for aparticular portion of device 10. Device 10 can be straightened orotherwise deformed through the application of force, then return to itspre-formed shape by virtue of the super-elasticity of shape wire 48after the removal of the deforming force. For example, distal tipassembly 40 can be straightened by manual force and inserted to theheart through an introducer. The introducer can maintain the deforming(straightening) force as device 10 is advanced through the introducer.As distal tip assembly 40 emerges from the introducer into the heart, itwould return to the pre-formed lariat shape of shape wire 48. In a shapememory embodiment, shape wire 48 can have a “naturally” straight shapebut form a pre-determined shape (such as the lariat shape of distal tipassembly 40) upon exposure to an increased temperature (such as in thehuman body). Although shape wire 48 is shown with a distal portion thatforms a lariat shape, shape wire 48 can be used to form a variety ofshapes within the scope and spirit of the present invention.Additionally, shape wire 48 can also be configured as a pull wire, suchthat the application of force at the proximal end of device 10 (such aspulling on wire 48) can alter the shape of distal tip assembly 40. Forexample, pulling on shape wire 48 can decrease the radius of the lariatshape.

One method of adding tip electrode 46 and shape wire 48 to device 10 isto pre-couple shape wire 48 with tip electrode 46, then thread shapewire 48 through lumen 44. In doing so, shaft 42 and one or more positionsensors—shown in outline form as 26 ₁ and 26 ₂ although within wall 50of shaft 42—must be guided over the curvature of shape wire 48. Shapewire 48 can include one or more sharp bends, such as bend 52, that canplace a large amount of stress on shaft 42 and any components disposedwithin wall 50. However, because sensors 26 ₁, 26 ₂ are within sleeves28 instead of embedded directly in wall 50, sensors 26 ₁, 26 ₂ can shiftand move relative to the portion of wall 50 surrounding each sensor 26,thereby reducing or eliminating the direct mechanical stress transmittedthrough wall 50 that would otherwise be imparted to each sensor 26. Inother words, each sensor 26 is tethered within wall 50, rather thanrigidly embedded in wall 50. Thus, each sensor 26 can be guided overbend 52 and other stress-inducing portions of shape wire 48 withoutbreaking Even though each sensor 26 can shift relative to the portion ofwall 50 surrounding the sensor 26, sleeve 28 and wiring 36 ensure thateach sensor remains in a predictable location for position sensing andnavigation purposes.

FIG. 10 is a cross-sectional view of the extreme distal end of distaltip assembly 40, taken substantially along line 10-10 in FIG. 9. Tipelectrode 42 can be coupled to the extreme distal tip of shaft 42through methods known in the art. Shape wire 48 can be coupled to aninner surface of tip electrode 46 through a metallurgical process suchas soldering, brazing, welding, or another process known in the art.Shape wire 48 can have a circular radial cross-section, or can have adifferent cross-section as needed for specific applications. Althoughtip assembly 40 has only one shape wire 48, more than one shape wire 48can be used. Each wire used can serve as either a shape wire having apre-determined shape, as a pull wire, or as both. For example, device 10can incorporate only a single shape/pull wire 48 as shown in FIG. 10, orcan have multiple shape and pull wires. A more detailed explanation ofshape wires and of joining a shape wire to a tip electrode can be foundin commonly-owned U.S. Pat. No. 7,706,891, entitled “Catheter EmployingShape Memory Alloy Shaping Wire or Pull Wire and Method of ItsManufacture,” hereby incorporated by reference in its entirety.

FIG. 11 is an isometric view of elongate medical device 10 havingcompleted distal tip assembly 40. Distal end portion 54 has a lariatshape according to the curvature of shape wire 48. After coupling tipelectrode 46 and shape wire 48 with assembly 40, assembly 40 can becompleted by various other steps known in the art or by adding otherfeatures known in the art, such as additional wiring, layers, or one ormore additional electrodes. For example, in addition to tip electrode46, distal end portion 54 can include 9 band electrodes (“decapolar”catheter) or 19 band electrodes (“duo-decapolar” catheter). A proximalend portion 56 of device 10 can provide the ability to connect device 10to navigation and mapping systems and power sources, as well as theability to manipulate distal end portion 54 of device 10.

In an exemplary embodiment of distal tip assembly 40, shaft 42 can havea desired inner diameter (ID) of about 0.048 inches and a desired outerdiameter (OD) of about 0.065 inches. In such an exemplary embodiment,first shaft layer segment 22 ₁ can have an ID of about 0.048 inches andan OD of about 0.050 inches. Sensor assembly 24 can have an OD of about0.013 inches. First shaft layer segments 22 ₂ and 22 ₃ can each have anID of about 0.048 inches and an OD of about 0.052 inches. Second shaftlayer 38 can have an ID of about 0.058 inches and an OD of about 0.062inches. First shaft layer 22 and second shaft layer 38 can both bePEBAX® material with a 55D durometer. After reflow lamination, theexemplary embodiment can have the desired ID, desired OD, and havesensor 26 tethered within wall 50.

Manufacturing distal tip assembly 40, distal end portion 54, and device10 according to the methods described in conjunction with FIGS. 2-11presents many advantages. Electromagnetic position sensor 26 is disposedwithin sleeve 28 such that sensor 26 can shift relative to sleeve 28.Accordingly, sensor 26 is not subjected to all of the stress placed onwall 50 as shaft 42 is threaded over shape wire 48. But because outersleeve 28—which contains sensor 26—is at least in part embedded in orotherwise substantially fixed to wall 50, the shifting and movement ofsensor 26 relative to wall 50 can remain within a certain tolerance suchthat sensor 26 can still reliably be used for position sensing anddevice navigation. As a result, one or more position sensors 26 can beincorporated into a medical device with a shape wire 48 of manydifferent shapes, such as a lariat shape in its distal end portion.

It should be understood that the embodiments of device 10, distal tipassembly 40, and distal end portion 54 are exemplary in nature.Variations could be made and still fall within the spirit and scope ofthe claimed invention. For example, distal tip assembly 40 can have one,two, three, or more position sensors 26 or position sensor assemblies24. Multiple sensors 26 or sensor assemblies 24 can require more firstshaft layer segments 22 ₁, . . . , 22 _(n) than specified in theembodiments herein. The lengths and thicknesses of shaft layers 22, 38can be configured for specific devices and applications. Similarly, thedurometer of shaft layers 22, 38 can be tailored to a specificapplication and the durometer of shaft 42 (and/or the entire shaft ofthe finished device) can vary over its length. Lumen 44 can be larger orsmaller than the embodiments described herein depending on the requireddimensions and features of a particular device. Other modifications andadditions known in the art can also be possible.

FIG. 12 is a side view of a distal end portion 58 of a second embodiment60 of an elongate medical device, with a portion of the outer jacket cutaway to show interior components. Device 60 includes a first embodimentof a flex circuit 62 for connecting wiring 36 to sensor 26. Wiring 36can have leads 64, consisting of a first free end and a second free end.Sensor leads 34 can also consist of a first free end and a second freeend. Flex circuit 62 can electrically connect the first free end ofwiring leads 64 to the first free end of sensor leads 34 to form a firstelectrical path and the second free end of wiring leads 64 to the secondfree end of sensor leads 34 to form a second electrical path whileelectrically separating the first and second electrical paths. Circuit62 can have a size and shape appropriate for the needed application.Flex circuit 62 can abut sensor 26 on one axial end (the distal end ofcircuit 62 in device 60) and can abut wiring 36 on the other axial end(the proximal end of circuit 62 in device 60). If wiring 36 has ashielding, housing, or other outer layer, as shown, flex circuit 62 canextend up to the outer layer or can extend partially into or adjacent tothe outer layer.

FIG. 13 is a cross-sectional view of catheter 60, taken substantiallyalong line 13-13 in FIG. 12. As in device 10, sensor 26 in catheter 60can be an electromagnetic coil sensor, including a tubular core 30 and acoil 32 wrapped around core 30. Flex circuit 62 can have a bend 66 tocreate contact surfaces in separate planes. A contact surface can have agreater radial dimension than axial dimension (“radial contact pad”), ora greater axial dimension than radial dimension (“axial contact pad”).Wiring leads 64 and sensor leads 34 can be coupled to circuit 62 throughsoldering or another electrically-conductive coupling method.

FIGS. 14-17 are various isometric and plan views of flex circuit 62.Circuit 62 can include an electrically-insulative substrate 78 and twosets of contact pads 68, 70 electrically connected by thin,electrically-conductive traces 72. Contact pads 68, 70 can be made of anelectrically-conductive material that can easily be coupled with wiringleads 64 and sensor leads 34, such as solder. Traces 72 can be anelectrically-conductive material, such as brass. Contact pads 68 can beaxial contact pads and can be provided at the proximal end of circuit 62for connection with wiring leads 64. Contact pads 70 can be radialcontact pads and can be provided at the distal end of circuit 62 forconnection with sensor leads 34. Substrate 78 can also have an axialextension portion 74 extending axially from contact pads 68. Axialextension portion 74 can have a length similar or substantially equal tothe length of associated leads, such as wiring leads 64. In an exemplaryembodiment, axial length L₄ of flex circuit 62 can be about 0.038inches, length L₅ of the contact portion (i.e., the portion of circuit62 including contact pads 68, 70, and traces 72) of circuit 72 can beabout 0.020 inches, and length L₆ of axial extension portion 74 can beabout 0.018 inches.

FIGS. 18-19 are plan views of a second embodiment 76 of a flex circuit.Circuit 76 performs the same functions as circuit 62 as described above,except where otherwise noted, but is slightly different in form. Circuit76 can include substrate 78 and two pairs or sets of contact pads 68,70, both of which are axial contact pads. Contact pads 68, 70 can bejoined by axially-extending electrically-conductive traces 72. Substrate78 can also include two axial extension portions 74 ₁, 74 ₂ (one at theproximal end of circuit 76 and one at the distal end). Circuit 76 can beused instead of circuit 62 when two axial extension portions aredesired, or when two sets of axial contact pads are desired.

In an embodiment of circuit 76, axial length L₇ of circuit 76 can beabout 0.072 inches. Length L₈ of the contact portion of circuit 76 canbe about 0.032 inches. Contact pads 68 can have an axial length of about0.010 inches, and contact pads 70 an axial length of about 0.004 inches.Traces 72 can have an axial length of about 0.0158 inches. Contact pads68, 70, and traces 72 can each have a width of about 0.002 inches.

Although only shown specifically with device 60, a flex circuit such asflex circuit 62 or flex circuit 76 can find use with any device forwhich electrical coupling between two sets of leads is desirable. Forexample, flex circuit 62 or 76 can be used in conjunction with elongatemedical device 10 as an interface to couple sensor 26 with wiring 36.

Although numerous embodiments of this invention have been describedabove with a certain degree of particularity, those skilled in the artcould make numerous alterations to the disclosed embodiments withoutdeparting from the spirit or scope of this invention. All directionalreferences (e.g., plus, minus, upper, lower, upward, downward, left,right, leftward, rightward, top, bottom, above, below, vertical,horizontal, clockwise, and counterclockwise) are only used foridentification purposes to aid the reader's understanding of the presentinvention, and do not create limitations, particularly as to theposition, orientation, or use of the invention. Joinder references(e.g., attached, coupled, connected, and the like) are to be construedbroadly and can include intermediate members between a connection ofelements and relative movement between elements. As such, joinderreferences do not necessarily infer that two elements are directlyconnected and in fixed relation to each other. It is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative only and not limiting.Changes in detail or structure can be made without departing from thespirit of the invention as defined in the appended claims.

What is claimed is:
 1. A method of fabricating a distal tip assembly foran elongate medical device having an axis, comprising: providing a firstshaft layer; placing, at a distal end portion of said elongate medicaldevice, a position sensor assembly on said first shaft layer, saidposition sensor assembly comprising a tubular core, anelectrically-conductive coil wound on said core, and an outer sleevesurrounding said core and said coil; applying a second shaft layerradially-outwardly of said position sensor assembly and said first shaftlayer; and subjecting said tip assembly to a reflow lamination process,wherein said first shaft layer and said second shaft layer bond to anouter surface of said sleeve, and said coil and said core can shiftwithin said sleeve.
 2. The method of claim 1, further comprising:coupling said coil to one or more wires; and extending said one or morewires axially toward a proximal end from said position sensor assembly.3. The method of claim 1, further comprising: coupling a tip electrodeto an extreme distal end of said distal end portion; placing a shapewire radially-inwardly of said first shaft layer; and coupling saidshape wire to said tip electrode.
 4. The method of claim 1, wherein saidfirst shaft layer and said second shaft layer comprise PEBAX material.5. The method of claim 1, wherein said outer sleeve comprises expandedpolytetrafluoroethylene (ePTFE).
 6. The method of claim 3, wherein saidshape wire comprises Nitinol.
 7. The method of claim 1, wherein an axiallength of said sleeve is greater than an axial length of said core.
 8. Amethod of fabricating an elongate medical device having an axis,comprising: placing a sensor assembly on a first portion of a firstshaft layer, wherein said first portion is proximate a second portionand a third portion of said first shaft layer; applying a second shaftlayer radially-outwardly of said sensor assembly and said first portion,said second portion, and said third portion of said first shaft layer;and bonding said second portion and said third portion of said firstshaft layer and said second shaft layer, wherein said sensor assemblycan shift relative to said second shaft layer.
 9. The method of claim 8,further comprising: coupling said sensor assembly to one or moreelectrical wires; and extending said one or more electrical wiresproximally from said sensor.
 10. The method of claim 8, furthercomprising: coupling a tip electrode to an extreme distal end of adistal end portion; placing a shape wire radially-inwardly of said firstshaft layer; and coupling said shape wire to said tip electrode.
 11. Themethod of claim 8, wherein said first shaft layer and said second shaftlayer comprise PEBAX material.
 12. The method of claim 8, wherein saidsensor assembly comprises a sensor comprising a tubular core and anelectrically-conductive coil wound on said core, the method furthercomprising: placing said sensor in an outer sleeve surrounding said coreand said coil.
 13. The method of claim 8, wherein said sensor assemblycomprises an outer sleeve, wherein applying said second shaft layerradially-outwardly of said sensor assembly and said first shaft layercomprises applying said second shaft layer radially-outwardly of saidouter sleeve.
 14. The method of claim 13, wherein said outer sleevecomprises expanded polytetrafluoroethylene (ePTFE).
 15. The method ofclaim 13, wherein bonding said first shaft layer and said second shaftlayer to an outer surface of said sensor assembly encapsulates saidouter sleeve.